Water repellent soil, whether in sandy areas or not, have proven to be the most difficult conditions in which plant life may be grown. Such a condition basically prevents or drastically reduces the ability of water to infiltrate from the ground level to subterranean root systems. In addition, environmental problems may occur as well due to surface runoff from rain, thereby transporting pesticides and/or fertilizers from the desired agriculture locations to ponds, lakes, reservoirs, or other undesirable water sources, as well as increasing the chances of ground water contamination therefrom.
Water content and soil particle size contribute to such water repellency issues, in addition to the presence of certain organic matter therein (humic acid, for example, as discussed in greater detail below). Such organic matter basically causes water repellency in the specific soils by imparting hydrophobic properties thereto while adhering to the soil particles themselves via hydrophilic constituents present within the particular organic matter.
In particular, localized dry spots are a distinct problem within highly managed turf areas and/or lawns, in particular those with sandy soils, primarily for aesthetic reasons. Such dry spots are the result of the development of areas of varying degrees of water repellency within and at the surface of the target soil. Plant water usage is critical to sustained plant growth; however, the existence of such localized dry spots creates a problem with nonuniformity of water supply to treated grasses over time. Basically, in times of high stress and/or easy water evaporation (e.g., higher temperatures, low humidity), such water repellency areas will exhibit higher water loss than others. As a result, the plant life present within the target lawn or green will not receive uniform, and, at times, vastly different levels of, water supply. As time passes, the difference in the amount of water supplied to discrete areas of the target lawn or green may become more disparate. Thus, the possibility for localized dry spots to materialize within sandy soils is relatively high over a sustained length of time (e.g., from 6 to 18 months on average from genesis to being empirically noticed), and, again, most times the existence of such dry spots is unknown to the lawn or green caretaker until materialization (since the presence of such water repellency areas may exist anywhere within the topsoil, from the surface to as low as about 2 inches below, the area of greatest concentration of grass root systems).
Also, hydrophobicity of sand creates certain problems with regard to pooling water after raining (as one example) which in turn causes unsightly areas either within highly sandy yards, ballparks, or beaches, or to provide water penetration in dry sandy conditions in order to possibly sustain plant-life therein (such as arid desert-like areas). Reduction in such water repellency would thus be helpful in maintaining, at least, better aesthetics for such sandy areas, as well as the possibility for permitting or promoting the growth of sustained plant life in such dry, barren areas.
Without intending to be bound to any particular scientific theory, it is believed that such water repellency areas within sandy soils are the result of the presence of humic substances and their attachment to soil components, particularly in large accumulations at the topsoil surface. Humus is degraded plant and animal matter (by microbial organisms) and is basically the organic portion of soil that comprises the necessary nutrients to sustain plant growth and life therein. One byproduct of such humus (again produced through a naturally occurring process within the soil) is humic acid (simply the acidic form of humus, basically a mix of various different materials). Humic acid and other like substances, although necessary for the sustenance of plant life as it provides the aforementioned nutrients to root systems, unfortunately also appears to create problems within sandy soils, most particularly the creation of a waxy organic, water-repellent coating upon binding to and with soil components (for instance, and without limitation, sand). If such a coating is permitted to accumulate over a long period of time, such as the aforementioned 6 to 18 month period, and particularly at the topsoil surface, the coating becomes highly water repellent in nature and uniform plant water use is difficult to achieve. In theory, and, again, without intending to be bound to such theory, it is believed that such a coating is formed by the amphiphylic humic acid (or other like humic substance) adhering, by its hydrophilic portion, to the hydrophilic sites within the sandy soil, permitting the highly hydrophobic ends to extend (similar in nature to a micelle). Such a coating is thus hydrophobic in nature and, when present as a thorough coating over such surface portions, again, tends to either drive water away or facilitate water loss by preventing moisture from passing through to the subterranean roots of any plants therein. If the water remains at the surface, evaporation is also facilitated as such moisture cannot easily penetrate the hydrohphobic soil surface. Such a problem exists, as noted above, not only within greens, but also within lawns and pastures (as merely some examples of such trouble areas). In order to provide a uniform appearance in lawns and greens, it has been a requirement either to water consistently in very large amounts (which is wasteful and possibly damaging to the plants themselves) or to water selected trouble areas by hand on a continuous basis (which is labor-intensive and possibly wasteful in terms of water consumption). Furthermore, it is generally too late to know of problematic water repellent areas within such lawns or greens until they become apparent empirically. For pastures, pools of water develop sporadically on occasion due to this problem; the standard method of remedying this problem is to dig up the earth and wait for the humic substances to be consumed as nutrients (over a relatively long period of time) by the root systems therein. Such a procedure thus leaves an aesthetically displeasing result and is not always reliable for reducing water repellency therein. Thus, it has been found that there exists a need to provide a simple method for providing effective moisture penetration through such highly hydrophobic coatings to ameliorate the lack of hydrophilicity, and thus water availability at the soil surface and within the subterranean root systems thereof without causing detrimental effects to the surface plant life.
In the past, the best methods of reducing the amount and presence of localized dry spots have basically involved the introduction of certain standard surfactants to the soil for the transport of water through the surface coating, preferably in tandem with compounds that decrease the surface tension of the waxy coating to permit penetration of the active surfactant components themselves in U.S. Pat. No. 5,921,023 to Ogawa et al., U.S. Pat. No. 5,595,957 to Bowey et al., and U.S. Pat. No. 5,731,268 to Taguchi et al. Such a method has been problematic to a certain extent due to the cost associated with some silicon-based surfactants, biodegradability issues of most viable surfactants, as well as foaming problems when water is present, and/or the difficulty in removal of degraded coating components after surfactant treatment. Also, this specific surfactant-only treatment does not remove the waxy coating to an appreciable degree from the target topsoil surface. Furthermore, prior surfactant treatments are limited in effectiveness due to the need for continued application thereof to target soils over a relatively short period of time for any sustained improvements in moisture penetration. A long-term (e.g., greater than 4 months, or a season) formulation applied in a single application or in split applications spaced 7 to 10 days apart and/or method for providing water repellency improvements are thus unavailable to the pertinent industry at this time.
Another manner of reducing such dry spot problems has been increasing watering itself. However, as noted above, such a method is labor intensive and, in many areas where water is not plentiful, use for aesthetic purposes (e.g., lawns, greens, and the like), is preferably kept at a minimum as compared to other more important purposes (e.g., drinking water). Such an issue also contributes to the aforementioned development of water repellency areas over long periods of time because of the inability of the caretaker to continuously supply moisture to target lawns, greens, etc., to the levels needed to best ensure uniformity of watering is accomplished. Other possible attempts at alleviating such a problem exist, albeit as an aim at removing contaminants (e.g., oils, fuels, etc.) from the target soils for improving plant growth therein (U.S. Pat. No. 6,090,896 to Jahnke et al. and WO01/26832 to Lubrizol Corporation). None of these procedures provide the necessary degree of wetting at the lower cost and/or labor intensity to overcome the hydrophobicity problems noted above. Wetter formulations applied in a single application or in split applications spaced 7 to 10 days apart to provide wetting methods for season-long consistent and continuous moisture penetration within such hydrophobic soils are nonexistent currently. Such a currently unavailable method and formulation providing such beneficial results are thus highly desirable to the soil treatment industry.